Unit 4 - Photosynthesis Flashcards

1
Q

Because they cannot make their own food, __________________ rely on the food making ability of green plants.

A

heterotrophs

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2
Q

Why is it accurate to say that heterotrophs rely indirectly on the sun for their energy?

A

Heterotrophs rely indirectly on the sun for their energy because the energy stored in the organic compounds they consume originally came from the sun, captured through photosynthesis by autotrophs.

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3
Q

Organisms that make their own food are called ________________ and therefore are the ________________ for the biosphere.

A

autotrophs, producers

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4
Q

Which of the following is not an autotroph
a. Some bacteria that photosynthesize
b. Algae
c. Tree
d. Mushroom

A

Mushroom
Mushrooms are heterotrophs that obtain their nutrients by decomposing organic matter or by parasitizing other organisms. They are not capable of producing their own food through photosynthesis.

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5
Q

Why is it important for organisms to acquire organic compounds?

A

It’s important for organisms to acquire organic compounds because they contain the necessary carbon and energy sources for growth, maintenance, and energy production within an organism.

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6
Q

Do both plants and animals perform cell respiration?

A

Yes, both plants and animals perform cell respiration. Cell respiration is the process by which cells break down organic molecules to produce ATP, the energy currency of the cell, for various cellular functions.

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7
Q

Do both plants and animals photosynthesize?

A

No, only plants perform photosynthesis. Animals **do not possess the necessary cellular structures **(like chloroplasts) or pigments (like chlorophyll) required to carry out photosynthesis. Instead, animals acquire energy by consuming organic matter, either plant-based or from other animals.

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8
Q

Where in the chloroplast does the light dependent reaction occur?

A

The light-dependent reactions occur in the thylakoid membranes of the chloroplast.

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9
Q

Where in the chloroplast does the light independent reaction occur?

A

The light-independent reaction occur in the stroma of the chloroplast.

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10
Q

The part of the leaf where most photosynthesis occurs is the:
a. Vein
b. Stomata
c. Mesophyll
d. Cuticle

A

c. Mesophyll

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11
Q

What role do the stomata play in photosynthesis?

A

Stomata play a crucial role in photosynthesis by regulating gas exchange. They open to allow the entry of carbon dioxide (CO2) needed for photosynthesis and the exit of oxygen produced during the process. They also control water vapor loss from the leaf.

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12
Q

What is the stroma

A

The stroma is the fluid-filled space inside the chloroplast, surrounding the thylakoid membranes.

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13
Q

What is the Thylakoid?

A

Thylakoids are membrane-bound compartments within chloroplasts. The light-dependent reaction occurs in the thylakoid. It contains chlorophyll and other pigments that absorb sunlight.

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14
Q

Why is the chloroplast compartmentalized by 3 membranes?

A

Chloroplasts are compartmentalized by three membranes to create distinct spaces for different stages of photosynthesis and to optimize efficiency. This compartmentalization helps separate processes like the movement of electrons during the light reactions in the thylakoid membrane and the Calvin cycle in the stroma.

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15
Q

What are the two major functions of veins (Xylem & phloem)?

A

Xylem transports water and minerals from the roots to the rest of the plant. Phloem transports the sugars produced during photosynthesis from the leaves to other parts of the plant.

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16
Q

Parts of the leaf and their function

A

Cuticle: A waxy layer on the leaf’s surface, reducing water loss.

Epidermis: The outer layer of cells protecting the leaf.

Mesophyll: The middle layer containing chloroplasts where photosynthesis occurs

Stomata: Holes on the leaf surface regulating gas exchange.

Veins (Xylem & Phloem): Transport systems for water, minerals, and sugars.

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17
Q

Parts of chloroplasts and their functions.

A

Thylakoid: Membrane-bound compartments where the light-dependent reactions occur.

Granum (plural: Grana): Stack of thylakoids.

Stroma: Fluid-filled space surrounding the thylakoids, where the Calvin cycle (light-independent reactions) occurs.

Inner membrane: Encloses the stroma.

Outer membrane: Encloses the entire chloroplast.

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18
Q

What are the two sets of reactions in photosynthesis called?

A

The two sets of reactions in photosynthesis are the light-dependent reactions (occurring in the thylakoid membranes) and the light-independent reactions or the Calvin cycle (taking place in the stroma).

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19
Q

What are the reactants and products of light dependent reaction?

A

Reactants: Water (H2O), ADP, NADP+
Products: Oxygen (O2), ATP, NADPH

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20
Q

Summarize what happens in light reaction

A

Light energy is absorbed by chlorophyll and other pigments in the thylakoid membranes. Water molecules are split (photolysis), releasing oxygen, protons (H+), and electrons. These electrons move through the electron transport chain, creating a proton gradient that drives ATP synthesis and reducing NADP+ to NADPH. Oxygen is released as a byproduct.

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21
Q

What are the reactants and products of light independent reaction?

A

Reactants: ATP, NADPH, CO2
Products: Glucose (C6H12O6), ADP, NADP+

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22
Q

Summarize what happens in the light independent reaction? (Calvin Cycle)

A

Carbon dioxide combines with a five-carbon molecule to make a six-carbon compound using an enzyme called Rubisco. This compound goes through a series of steps using energy from light to produce sugars like glucose. In the process, some molecules like** ATP** and NADPH are **used and recycled **to keep the cycle going.

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23
Q

Write the overall balanced equation for photosynthesis.

A

6CO2 + 6H2O → C6H12O6 + 6O2

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24
Q

Why is carbon dioxide essential in the process of photosynthesis?

A

Carbon dioxide (CO2) is essential in photosynthesis because it provides the carbon source for glucose and other organic molecules synthesized during the light-independent reactions (Calvin cycle). Through a series of enzyme-driven reactions, CO2 is fixed and converted into organic compounds, utilizing the energy from ATP and NADPH produced in the light-dependent reactions. This process is crucial to produce carbohydrates and the overall synthesis of organic molecules by plants.

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25
Q

Describe the three things that could happen to light of a particular wavelength after it strikes a leaf.

A

1.) It can be absorbed by pigments like chlorophyll, transferring its energy to fuel photosynthesis.
2.) It might be reflected off the leaf’s surface, giving the leaf its color and potentially not contributing to photosynthesis.
3.) Some wavelengths could pass through the leaf or be transmitted, depending on their intensity and the leaf’s structure.

26
Q

Why are wavelengths of electromagnetic energy that are shorter than visible light not good for photosynthesis?

A

They possess excessive energy that can damage the chlorophyll molecules and other essential components involved in photosynthesis.

27
Q

Why are wavelengths of electromagnetic energy that are longer than visible light not good for photosynthesis?

A

Wavelengths of electromagnetic energy longer than visible light (like infrared radiation) have lower energy levels, and while they contribute to heating the leaf and its surroundings, they do not possess the necessary energy to effectively drive the photosynthetic reactions. Therefore, they are not efficient in stimulating the processes required for photosynthesis.

28
Q

What are the two major wavelengths of light most important to photosynthesis?

A

Red light: This wavelength is critical for the activation of chlorophyll and the photosynthetic process.

Blue light: Essential for the proper functioning of chlorophyll and other pigments, playing a significant role in regulating plant growth and photosynthesis.

29
Q

What is the major pigment molecule in photosynthesis?

A

The major pigment molecule in photosynthesis is chlorophyll.

30
Q

Why does a leaf containing chloroplasts look green in color?

A

A leaf containing chloroplasts looks green in color because chlorophyll, the primary pigment in chloroplasts, absorbs most wavelengths of visible light except for green. Green light is reflected or transmitted, giving the leaf its green appearance.

31
Q

A friend challenges you to grow a houseplant using mainly one color of light. -either green or red. Which would you choose? Explain your answer.

A

For growing a houseplant using mainly one color of light, I would choose red light. While green light is not efficiently absorbed by chlorophyll (as seen in the color of leaves), red light is crucial for photosynthesis. It’s within the spectrum of light that chlorophyll can readily absorb, making it more effective for plant growth compared to green light.

32
Q

What is a pigment molecule?

A

A pigment molecule is a molecule that absorbs specific wavelengths of light and appears colored due to the wavelengths it reflects. These pigments are essential in photosynthesis as they capture light energy and transfer it to reaction centers, initiating the process of converting light energy into chemical energy.

33
Q

Where is the pigment molecule, chlorophyll, found?

A

Chlorophyll is found within chloroplasts, primarily in the thylakoid membranes where it plays a central role in capturing light energy during photosynthesis.

34
Q

Are there accessory pigment in a photosystem that help capture more light?

A

Yes, there are accessory pigments in a photosystem that aid in capturing more light.

35
Q

Does the production of NADPH and NADP+ and ATP from ADP require sunlight?

A

Yes, the production of NADPH from NADP+ and ATP from ADP requires sunlight, specifically during the light-dependent reaction(s) of photosynthesis.

36
Q

Why doesn’t photosynthesis stop with the production of the energy storing compounds NADPH and ATP?

A

Photosynthesis doesn’t stop with the production of NADPH and ATP because these molecules serve as energy carriers that are used in the subsequent reactions of the Calvin cycle (light-independent reactions) to convert carbon dioxide into glucose and other organic compounds.

37
Q

Describe a photosystem

A

A photosystem is a cluster of pigments, including chlorophyll, and proteins located in the thylakoid membrane of chloroplasts. It’s responsible for capturing light energy during the light-dependent reactions of photosynthesis.

38
Q

Where are photosystems located?

A

Photosystems are located in the** thylakoid membranes** of chloroplasts.

39
Q

How many types of photosystems are there in green plants?

A

In green plants, there are two types of photosystems: Photosystem I (PSI) and Photosystem II (PSII).

40
Q

How does the energy of sunlight get from the chlorophyll molecule to the electron transport chain?

A

Energy derived from sunlight energizes an electron in the green organic pigment chlorophyll, enabling the electron to move along an electron-transport chain.

41
Q

How is oxygen produced?

A

Oxygen is produced during the** light-dependent reactions** of photosynthesis through the process of photolysis, where water molecules are split into oxygen, protons (H+), and electrons. This occurs in Photosystem II.

42
Q

How does chlorophyll in reaction center replace electrons lost to NADPH?

A

Chlorophyll in the reaction center replaces electrons lost to NADPH by accepting electrons from a donor molecule within the photosystem.

43
Q

How does chlorophyll in reaction center replace electrons lost to the electron transport chain responsible for making ATP?

A

Chlorophyll in the reaction center replaces electrons lost to the electron transport chain responsible for making ATP by receiving electrons from water molecules during the process of photolysis.

44
Q

Give three reasons why the splitting of water is vital to photosynthesis

A

1.) It provides electrons that replace those lost by chlorophyll in the photosystems.
2.) It releases oxygen as a byproduct, essential for many organisms.
3.) It generates protons (H+) that contribute to the proton gradient used in ATP synthesis during photophosphorylation.

45
Q

Describe what occurs in the electron transport chain?

A

In the electron transport chain, energized electrons move through a series of protein complexes embedded in the thylakoid membrane. As these electrons pass through the chain, energy is used to pump protons from the stroma into the thylakoid lumen, creating a proton gradient.

46
Q

What happen at the end of the electron transport chain?

A

At the end of the electron transport chain, electrons combine with NADP+ and protons (H+) to form NADPH.

47
Q

Name two things being added to NADP+

A

Two things being added to NADP+ are electrons and protons (H+) to form NADPH.

48
Q

Which molecule vital to life is released as a waste product of photosynthesis during light reaction?

A

Oxygen, a molecule vital to life, is released as a waste product of photosynthesis during the light reaction through the process of photolysis.

49
Q

Which of the following are not produced during the light reaction?
a. Glucose
b. Hydrogen ions
c. Oxygen
d. ATP
e. NADPH

A

Glucose

50
Q

Describe how ATP is generated during the light reaction (Chemiosmosis).

A

ATP is generated during the light reaction through chemiosmosis. As protons accumulate in the thylakoid lumen, they flow back through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate.

51
Q

Why is it important that plants have a constant supply of water?

A

Plants need a constant supply of water for photosynthesis because water is the source of electrons in the light-dependent reactions.

52
Q

Where are photosystems I and II found?

A

Photosystem I and Photosystem II are found in the thylakoid membranes of chloroplasts, with Photosystem II preceding Photosystem I in the electron transport chain.

53
Q

Can the dark reactions take place during daylight?

A

Yes, the dark reactions (Calvin cycle) can take place during daylight, as they do not directly require light to occur. However, they rely on the products (ATP and NADPH) generated from the light-dependent reactions that occur during daylight.

54
Q

What serves as the source of carbon for the synthesis of organic molecules?

A

Carbon dioxide (CO2) serves as the source of carbon for the synthesis of organic molecules in the Calvin cycle.

55
Q

Why are the light reactions essential to the Calvin cycle?

A

The light reactions are essential to the Calvin cycle because they provide the ATP and NADPH required for the synthesis of organic molecules (such as glucose) in the Calvin cycle.

56
Q

What three substances must be supplied to the Calvin cycle?

A

The three substances supplied to the Calvin cycle are ATP, NADPH, and carbon dioxide (CO2).

57
Q

How many turns of the Calvin cycle is required to make one glucose molecule?

A

Six turns of the Calvin cycle are required to make one glucose molecule.

58
Q

What is carbon fixation?

A

Carbon fixation is the initial step of the Calvin cycle where atmospheric carbon dioxide (CO2) is incorporated and converted into organic compounds.

59
Q

What enzyme is responsible for carbon fixation?

A

The enzyme responsible for carbon fixation in the Calvin cycle is RuBisCO.

60
Q

What molecule does the Calvin cycle begin and end with?

A

The Calvin cycle begins and ends with RuBP

61
Q

What is the name of the energy poor three-carbon molecule in the Calvin cycle?

A

The energy-poor three-carbon molecule in the Calvin cycle is 3-PGA (3-phosphoglycerate).

62
Q

What is the name of the energy rich three-carbon molecule in the Calvin cycle? What made it energy rich?

A

The energy-rich three-carbon molecule in the Calvin cycle is G3P (glyceraldehyde-3-phosphate). Its energy richness comes from the ATP and NADPH used to convert 3-PGA into G3P during the reduction phase of the cycle.